|
|
Using simulation to predict defects in and cast Al-alloy castings
Šolc, Petr ; Bařinová, Dagmar (referee) ; Čech, Jaroslav (advisor)
The aim of this work is comparing three casting process simulation programs for porosity and microstructure prediction capabilities for die-casting. After confronting these results with experimentally measured data taken from real castings it could be said that simulation is pretty accurate for DAS microstructure prediction and hot-spot areas. Amount of measured porosity could not be compared with predicted values because specimens were not taken from the exact hot-spot areas.
|
|
|
DNA damage response in Huntington disease
Vachová, Veronika ; Šolc, Petr (advisor) ; Roth, Jan (referee)
Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder, which leads to loss of striatal neurons in basal ganglias. It is characterized by involuntary movements and progressive cognitive impairment. HD is a relatively rare disease and the prevalence is approximately 0,01 % of the population of Western European. HD is caused by a CAG repeat expansion in the huntingtin gene (HTT). This mutation results in an elongated stretch of glutamin. Mutant huntingtin (mHTT) expression leads to accumulation of DNA double-strand breaks (DSB) due to reduced ability of effective reparation, which contributes to the pathogenesis of HD, however this mechanism is not fully understood. There are several angles of view how mHTT impaires DNA damage response (DDR). Some studies say that the expression of the mHTT initiates excessive activation of the DDR including p53 signaling pathway leading to apoptosis. Other studies represent results for dysfunction of non-homologous end joining after recognition of DSB or that the cell is not able to recognize DSB. All theories would explain cell death as a consequence of high level of unrepaired DNA damage. The understanding of these mechanisms is important for the development of therapeutical strategies. Key words: Huntington's disease, huntingtin, DNA...
|
|
|
The roles of Trim15 and UCHL3 in the ubiquitin-mediated cell cycle regulation.
Jeřábková, Kateřina ; Chawengsaksophak, Kallayanee (advisor) ; Šolc, Petr (referee) ; Thorpe, Peter (referee)
(ENGLISH) Ubiquitin signaling is a key regulatory mechanism for many important cellular processes such as transcription, differentiation and cell division. Cell division requires duplication of all genetic material during S-phase followed by its precise partitioning between two daughter cells during mitosis. Misregulation of the complex mitotic machinery may lead to aneuploidy and genomic instability, known drivers of tumorigenesis. Indeed, systematic genetic analysis of many cancer tissues over the last decades, indicates the presence of severe chromosome abnormalities in thousands of cancer tissue samples. In this work, I investigated the function of two components of ubiquitin signaling, the deubiquitinating enzyme UCHL3 and the E3 ubiquitin ligase TRIM15. The hypothesized role of E3 ligase TRIM15 in the cell cycle regulation could not be confirmed by our experiments, but I observed an effect on cell adhesion and motility instead. UCHL3 was identified using high-content visual siRNA screen, as a critical factor controlling genome segregation and integrity. Interestingly, it has been previously reported that UCHL3 levels are altered in various cancer types, especially colon cancer. My data demonstrate that UCHL3 drives proper alignment of chromosomes at the metaphase plate by facilitating...
|
|
|
The involvement of mitotic kinases AURKA and PLK1 in the oocyte meiotic maturation
Brzáková, Adéla ; Šolc, Petr (advisor) ; Šebková, Nataša (referee)
Aurora A and Plk1 belongs to the extended family of serine/threonine kinases controlling the cell cycle. Both are involved in the control of mitosis and contribute also to the regulation of meiotic division. Although the role of Aurora A in the resumption of meiosis after the first meiotic block seems to be, according to present studies, a bit questionable matter, it is virtually certain that AURKA plays an irreplaceable role in the construction of the spindle. In the oocytes with inhibited (by RNAi or small molecular inhibitors) or overexpressed Aurora A, abnormal spindles with aberrant number of poles or otherwise unusually shaped spindles are created. Disruption of Plk1 function in oocytes also leads to the appearance of damaged spindles. In addition, Plk1, almost certainly, plays a role in the timing of the nuclear membrane breakdown - at GVBD.
|
|
|
Genomic instability associated with formation of RNA:DNA hybrids and molecular mechanisms of its suppression
Naščáková, Zuzana ; Dobrovolná, Jana (advisor) ; Hanzlíková, Hana (referee) ; Šolc, Petr (referee)
One of the most common infections of a human organism is an infection of stomach induced by pathogenic bacteria Helicobacter pylori (H. pylori). It is estimated that every second person is infected, with even higher prevalence in developing countries. As a quiet enemy, H. pylori can colonise a human stomach for decades without manifestation of infection-associated symptoms. However, chronic infection may cause severe damage to the stomach tissue, subsequently leading to the development of gastric diseases, including gastritis and ulcer disease. H. pylori infection is also a driving cause of gastric cancer, with 80% of gastric cancers being associated with chronic infection. H. pylori ensures its life-long persistence in a human host organism via the action of its virulence factors, which have a pleiotropic effect on multiple systems, mostly acting on the attenuation of a human immune system and the induction of atrophy of stomach tissue. The irreversible changes of stomach epithelium are induced by activation of an innate immune response in H. pylori-exposed epithelial cells through the stimulation of ALPK1/TIFA/NF-κB signalling pathway upon a recognition of β-ADP heptose, an intermediate product of bacterial lipopolysaccharide biosynthesis, and consequently leading to the formation of DNA...
|
|
|
Cell signaling pathways controlling meiotic maturation of mammalian oocytes
Šolc, Petr
5 2 Summary The female germ cells called oocytes arise from the primordial germ cells during embryogenesis. They are essential for the reproduction. Already during embryogenesis oocytes enter meiosis, however, they arrest at the dictyate stage of prophase I. After onset of sexual maturity luteinizing hormone induces the resumption of meiosis of follicle enclosed oocytes (GV stage) in animals (in vivo) but removing of oocytes from follicles and culture in a suitable medium allows the spontaneous resumption of meiosis in vitro. Nuclear envelope break down (NEBD or GVBD) is the first visible mark of the meiosis resumption. Later after GVBD, the metaphase I (MI) spindle forms and after all chromosome bivalents are correctly attached to microtubules (MTs) anaphase I occurs. Following meiosis I completion, oocytes enter directly meiosis II and arrest at metaphase II (MII). These oocytes are fertilizable and sperm trigger meiosis II completion. The development from GV to MII oocytes is governed mainly by meiosis promoting factor (MPF) that consists of cyclin dependent kinase 1 (CDK1) and cyclin B (CCNB). On the mouse oocytes, we have shown using functional studies (RNA interference, mRNA microinjection) that phosphatases CDC25A and B cooperate in the induction of CDK1 activity and resumption of meiosis. After...
|
|
|
Genomic instability associated with formation of RNA:DNA hybrids and molecular mechanisms of its suppression
Naščáková, Zuzana ; Dobrovolná, Jana (advisor) ; Hanzlíková, Hana (referee) ; Šolc, Petr (referee)
One of the most common infections of a human organism is an infection of stomach induced by pathogenic bacteria Helicobacter pylori (H. pylori). It is estimated that every second person is infected, with even higher prevalence in developing countries. As a quiet enemy, H. pylori can colonise a human stomach for decades without manifestation of infection-associated symptoms. However, chronic infection may cause severe damage to the stomach tissue, subsequently leading to the development of gastric diseases, including gastritis and ulcer disease. H. pylori infection is also a driving cause of gastric cancer, with 80% of gastric cancers being associated with chronic infection. H. pylori ensures its life-long persistence in a human host organism via the action of its virulence factors, which have a pleiotropic effect on multiple systems, mostly acting on the attenuation of a human immune system and the induction of atrophy of stomach tissue. The irreversible changes of stomach epithelium are induced by activation of an innate immune response in H. pylori-exposed epithelial cells through the stimulation of ALPK1/TIFA/NF-κB signalling pathway upon a recognition of β-ADP heptose, an intermediate product of bacterial lipopolysaccharide biosynthesis, and consequently leading to the formation of DNA...
|
|
|
The effect of maternal age on the level of DNA damage in oocytes
Koubovská, Markéta ; Šolc, Petr (advisor) ; Tlapáková, Tereza (referee)
Female germ cells are oocytes, whose number defines the length of the reproductive period. Besides quantity the quality of oocytes is also an important factor. The quality is not the same throughout whole life, but it decreases with increasing age. The loss of quality is mainly due to the accumulation of DNA damage. The most serious damage is considered to be double-strand breaks (DSBs) because of both DNA strands break and subsequent translocation or deletion. There are also products caused by reactive oxygen species, UV or γ radiation, modified DNA section or mismatch sequence. All these lesions are repaired by oocyte repair mechanisms. However, the older a woman is, the more gene expression of DNA repair genes is decreased. That is why the repair is not efficient and DNA damage is not removed. Higher age is associated with unsuccessful attempts to conceive, a higher risk of miscarriage or an ectopic pregnancy. To avoid the risks that pregnancy in old age represents, the reproductive ability has been lost. In humans, it ends around the age of 50 with so- called menopause.
|
|
|
The roles of Trim15 and UCHL3 in the ubiquitin-mediated cell cycle regulation.
Jeřábková, Kateřina ; Chawengsaksophak, Kallayanee (advisor) ; Šolc, Petr (referee) ; Thorpe, Peter (referee)
(ENGLISH) Ubiquitin signaling is a key regulatory mechanism for many important cellular processes such as transcription, differentiation and cell division. Cell division requires duplication of all genetic material during S-phase followed by its precise partitioning between two daughter cells during mitosis. Misregulation of the complex mitotic machinery may lead to aneuploidy and genomic instability, known drivers of tumorigenesis. Indeed, systematic genetic analysis of many cancer tissues over the last decades, indicates the presence of severe chromosome abnormalities in thousands of cancer tissue samples. In this work, I investigated the function of two components of ubiquitin signaling, the deubiquitinating enzyme UCHL3 and the E3 ubiquitin ligase TRIM15. The hypothesized role of E3 ligase TRIM15 in the cell cycle regulation could not be confirmed by our experiments, but I observed an effect on cell adhesion and motility instead. UCHL3 was identified using high-content visual siRNA screen, as a critical factor controlling genome segregation and integrity. Interestingly, it has been previously reported that UCHL3 levels are altered in various cancer types, especially colon cancer. My data demonstrate that UCHL3 drives proper alignment of chromosomes at the metaphase plate by facilitating...
|
|
|
Role of Rad18 in genome stability
Palek, Matouš ; Macůrek, Libor (advisor) ; Šolc, Petr (referee)
Rad18 is an E3 ubiquitin ligase well-known for its function in DNA damage tolerance (DDT). Especially, its role in translesion DNA synthesis, one of two DDT branches, was extensively studied in the past. Recently, Rad18 was shown to be involved in the repair of DNA double- strand breaks (DSBs) in mammalian cells. The role of Rad18 in human cells seems to be important since DSB repair as well as DDT pathway are essential for maintenance of genome stability. In this work, I introduce the function of Rad18 in both DDT pathways, translesion DNA synthesis (TLS) and template switching (TS). Then I summarize current knowledge about the role of human Rad18 in DSB repair. Finally, I describe potential involvement of Rad18 dysregulation in human cancer, since loss of genome integrity is an important driving force for tumorigenesis. Keywords: Rad18, genome stability, DNA double-strand break repair, tumorigenesis, DNA damage tolerance, translesion DNA synthesis, template switching.
|
guest ::
RSS feed.